Treprostinil derivatives and compositions and uses thereof

ABSTRACT

The present disclosure provides treprostinil derivatives that can act as prodrugs of treprostinil. The treprostinil derivatives can be used to treat any conditions responsive to treatment with treprostinil, including pulmonary hypertension, such as pulmonary arterial hypertension.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 16/880,146 (now U.S. Pat. No. 10,988,435) filed on May 21, 2020, which is a continuation of U.S. application Ser. No. 16/270,965 (now U.S. Pat. No. 10,703,706) filed on Feb. 8, 2019, which is a continuation of U.S. application Ser. No. 15/735,546 (now U.S. Pat. No. 10,246,403) filed on Dec. 11, 2017, which is a U.S. national-stage application of PCT/US2016/037383 filed on Jun. 14, 2016, which is a continuation in part of U.S. application Ser. No. 14/829,180 (now U.S. Pat. No. 9,643,911) filed on Aug. 18, 2015, which is a continuation in part of U.S. application Ser. No. 14/742,544 (now U.S. Pat. No. 9,394,227) and Ser. No. 14/742,579, both filed on Jun. 17, 2015. All of the prior applications are incorporated herein by reference in their entirety for all purposes.

BACKGROUND OF THE DISCLOSURE

Pulmonary hypertension (PH), which includes pulmonary arterial hypertension (PAH), is a disease that can result in death and is characterized by increased pulmonary artery pressure and pulmonary vascular resistance. Some drugs that can be used to treat PH or PAH cannot be effectively administered orally for various reasons and are generally administered via subcutaneous, intravenous or intramuscular routes. These routes of administration generally require intervention by a healthcare professional, and can entail considerable discomfort as well as potential local trauma to the patient.

One example of such a drug is treprostinil. Treprostinil as the free acid has an absolute oral bioavailability of less than 10% and a very short systemic half-life due to significant metabolism. Treprostinil can be administered in an inhaled form, but about 50% of PAH patients cannot take inhaled treprostinil due to irritation. Treprostinil (also called Compound A herein) has the following structure:

Treprostinil can exist as a salt, such as a sodium or diethanolamine salt.

SUMMARY OF THE DISCLOSURE

The present disclosure describes treprostinil derivatives that can act as prodrugs and provide increased systemic availability of treprostinil. In some embodiments, treprostinil derivatives have the structure of Formula (I):

wherein R¹ and R² independently are hydrogen,

and R³, R⁴, R⁵, R⁶, R⁹, R¹⁰, j, m and t are as described herein, or pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs or stereoisomers thereof, with the proviso that:

both R¹ and R² are not hydrogen;

neither —OR¹ nor —OR² forms an acetate;

neither —OR¹ nor —OR² forms a benzoate;

neither —OR¹ nor —OR² forms a substituted cyclohexane-ester;

neither —OR¹ nor —OR² forms an ester with or of an amino acid (protected or unprotected), a peptide or a protein; and

a compound of Formula (I) is not a homopolymer or heteropolymer of treprostinil, or does not contain more than one molecule or unit of treprostinil.

In other embodiments, treprostinil derivatives have the structure of Formula (II):

wherein —O—Z—CO₂H is

—O-heteroalkyl-CO₂H, —O-cyclyl-CO₂H, —O—CH₂-cyclyl-CO₂H, —O-cyclyl-CH₂—CO₂H, or —O—CH₂-cyclyl-CH₂—CO₂H, each of which may optionally be substituted, and -cyclyl-, -heteroalkyl-, R⁷, R⁸ and n are as described herein, with the proviso that:

—O—Z—CO₂H is not

and

—O—Z—CO₂H does not contain a sugar moiety.

The treprostinil derivatives can be used to treat any conditions responsive to treatment with treprostinil, including pulmonary hypertension (e.g., PAH). In some embodiments, the treprostinil derivatives are administered topically, such as transdermally (e.g., via a transdermal patch).

DETAILED DESCRIPTION OF THE DISCLOSURE

While various embodiments of the present disclosure are described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only.

Numerous modifications and changes to, and variations and substitutions of, the embodiments described herein will be apparent to those skilled in the art without departing from the disclosure. It is understood that various alternatives to the embodiments described herein may be employed in practicing the disclosure. It is also understood that every embodiment of the disclosure may optionally be combined with any one or more of the other embodiments described herein which are consistent with that embodiment.

Where elements are presented in list format (e.g., in a Markush group), it is understood that each possible subgroup of the elements is also disclosed, and any one or more elements can be removed from the list or group.

It is also understood that, unless clearly indicated to the contrary, in any method described or claimed herein that includes more than one act or step, the order of the acts or steps of the method is not necessarily limited to the order in which the acts or steps of the method are recited, but the disclosure encompasses embodiments in which the order is so limited.

It is further understood that, in general, where an embodiment in the description or the claims is referred to as comprising one or more features, the disclosure also encompasses embodiments that consist of, or consist essentially of, such feature(s).

It is also understood that any embodiment of the disclosure, e.g., any embodiment found within the prior art, can be explicitly excluded from the claims, regardless of whether or not the specific exclusion is recited in the specification.

Headings are included herein for reference and to aid in locating certain sections. Headings are not intended to limit the scope of the embodiments and concepts described in the sections under those headings, and those embodiments and concepts may have applicability in other sections throughout the entire disclosure.

All patent literature and all non-patent literature cited herein are incorporated herein by reference in their entirety to the same extent as if each patent literature or non-patent literature were specifically and individually indicated to be incorporated herein by reference in its entirety.

I. DEFINITIONS

As used in the specification and the appended claims, the indefinite articles “a” and “an” and the definite article “the” can include plural referents as well as singular referents unless specifically stated otherwise.

The term “about” or “approximately” means an acceptable error for a particular value as determined by one of ordinary skill in the art, which depends in part on how the value is measured or determined. In certain embodiments, the term “about” or “approximately” means within one standard deviation. In some embodiments, when no particular margin of error (e.g., a standard deviation to a mean value given in a chart or table of data) is recited, the term “about” or “approximately” means that range which would encompass the recited value and the range which would be included by rounding up or down to the recited value as well, taking into account significant figures. In certain embodiments, the term “about” or “approximately” means within 10% or 5% of the specified value. Whenever the term “about” or “approximately” precedes the first numerical value in a series of two or more numerical values or in a series of two or more ranges of numerical values, the term “about” or “approximately” applies to each one of the numerical values in that series of numerical values or in that series of ranges of numerical values.

Whenever the term “at least” or “greater than” precedes the first numerical value in a series of two or more numerical values, the term “at least” or “greater than” applies to each one of the numerical values in that series of numerical values.

Whenever the term “no more than” or “less than” precedes the first numerical value in a series of two or more numerical values, the term “no more than” or “less than” applies to each one of the numerical values in that series of numerical values.

The term “pharmaceutically acceptable” refers to a substance (e.g., an active ingredient or an excipient) that is suitable for use in contact with the tissues and organs of a subject without excessive irritation, allergic response, immunogenicity and toxicity, is commensurate with a reasonable benefit/risk ratio, and is effective for its intended use. A “pharmaceutically acceptable” excipient or carrier of a pharmaceutical composition is also compatible with the other ingredients of the composition.

The term “therapeutically effective amount” refers to an amount of a compound that, when administered to a subject, is sufficient to prevent development of, or to alleviate to some extent, the medical condition being treated or one or more symptoms associated with the condition. The term “therapeutically effective amount” also refers to an amount of a compound that is sufficient to elicit the biological or medical response of a cell, tissue, organ, system, animal or human which is sought by a researcher, veterinarian, medical doctor or clinician.

The terms “treat”, “treating”, and “treatment” include alleviating or abrogating a medical condition or one or more symptoms associated with the condition, and alleviating or eradicating one or more causes of the condition. Reference to “treatment” of a condition is intended to include prevention of the condition. The terms “prevent”, “preventing”, and “prevention” include precluding or delaying the onset of a medical condition or one or more symptoms associated with the condition, precluding a subject from acquiring a condition, and reducing a subject's risk of acquiring a condition. The term “medical conditions” includes diseases and disorders.

The term “subject” refers to an animal, including but not limited to a mammal, such as a primate (e.g., a human, a chimpanzee and a monkey), a rodent (e.g., a rat, a mouse, a gerbil and a hamster), a lagomorph (e.g., a rabbit), a swine (e.g., a pig), an equine (e.g., a horse), a canine (e.g., a dog) and a feline (e.g., a cat). The terms “subject” and “patient” are used interchangeably herein in reference to, e.g., a mammalian subject, such as a human subject.

The term “compound” encompasses salts, solvates, hydrates, clathrates and polymorphs of that compound. A “solvate” of a compound includes a stoichiometric or non-stoichiometric amount of a solvent (e.g., water, acetone or an alcohol [e.g., ethanol]), bound non-covalently to the compound. A “hydrate” of a compound includes a stoichiometric or non-stoichiometric amount of water bound non-covalently to the compound. A “clathrate” of a compound contains molecules of a substance (e.g., a solvent) enclosed in the crystal structure of the compound. A “polymorph” of a compound is a crystalline form of the compound. The specific recitation of “salt”, “solvate”, “hydrate”, “clathrate” or “polymorph” with respect to a compound in certain instances of the disclosure shall not be interpreted as an intended omission of any of these forms in other instances of the disclosure where the term “compound” is used without recitation of any of these forms.

The terms “sugar” and “saccharide” are used interchangeably herein.

The terms “halogen”, “halide” and “halo” refer to fluoride, chloride, bromide and iodide.

The term “alkyl” refers to a linear or branched, saturated monovalent hydrocarbon radical, wherein the alkyl group may optionally be substituted with one or more substituents as described herein. In certain embodiments, an alkyl group is a linear saturated monovalent hydrocarbon radical that has 1 to 20 (C₁₋₂₀), 1 to 10 (C₁₋₁₀), or 1 to 6 (C₁₋₆) carbon atoms, or is a branched saturated monovalent hydrocarbon radical that has 3 to 20 (C₃₋₂₀), 3 to 10 (C₃₋₁₀), or 3 to 6 (C₃₋₆) carbon atoms. As an example, the term “C₁₋₆ alkyl” refers to a linear saturated monovalent hydrocarbon radical of 1 to 6 carbon atoms or a branched saturated monovalent hydrocarbon radical of 3 to 6 carbon atoms.

Linear C₁₋₆ and branched C₃₋₆ alkyl groups may also be referred to as “lower alkyl”. Non-limiting examples of alkyl groups include methyl, ethyl, propyl (including all isomeric forms, such as n-propyl and isopropyl), butyl (including all isomeric forms, such as n-butyl, isobutyl, sec-butyl and tert-butyl), pentyl (including all isomeric forms, such as n-pentyl), and hexyl (including all isomeric forms, such as n-hexyl).

The terms “alkylene” and “-alkyl-” refer to a divalent alkyl group, which may optionally be substituted with one or more substituents as described herein.

The term “heteroalkyl” refers to a linear or branched, saturated monovalent hydrocarbon group containing one or more heteroatoms independently selected from O, N and S. The terms “heteroalkylene” and “-heteroalkyl-” refer to a divalent heteroalkyl group. A heteroalkyl group and a -heteroalkyl- group may optionally be substituted with one or more substituents as described herein. Examples of heteroalkyl and -heteroalkyl- groups include without limitation —(CH₂)₂—(O or S)—CH₂CH₃ and —(CH₂)₂—(O or S)—(CH₂)₂—.

The term “alkoxy” refers to an —O-alkyl group, which may optionally be substituted with one or more substituents as described herein.

The term “haloalkyl” refers to an alkyl group that is substituted with one or more halide atoms. A haloalkyl group may optionally be substituted with one or more additional substituents as described herein.

The term “-alkylaryl” refers to an alkyl group that is substituted with one or more aryl groups. An -alkylaryl group may optionally be substituted with one or more additional substituents as described herein.

The term “cycloalkyl” refers to a cyclic saturated, bridged or non-bridged monovalent hydrocarbon radical, which may optionally be substituted with one or more substituents as described herein. In certain embodiments, a cycloalkyl group has from 3 to 10 (C₃₋₁₀), or from 3 to 8 (C₃₋₈), or from 3 to 6 (C₃₋₆) carbon atoms. Non-limiting examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, decalinyl and adamantyl.

The term “-cycloalkyl-” refers to a divalent cycloalkyl group, which may optionally be substituted with one or more substituents as described herein.

The terms “heterocyclyl” and “heterocyclic” refer to a monocyclic non-aromatic group or a multicyclic group that contains at least one non-aromatic ring, wherein at least one non-aromatic ring contains one or more heteroatoms independently selected from O, N and S. The non-aromatic ring containing one or more heteroatoms may be attached or fused to one or more saturated, partially unsaturated or aromatic rings. In certain embodiments, a heterocyclyl or heterocyclic group has from 3 to 15, or 3 to 12, or 3 to 10, or 3 to 8, or 3 to 6 ring atoms. In some embodiments, a heterocyclyl or heterocyclic group is a monocyclic, bicyclic or tricyclic ring system, which may include a fused or bridged ring system, and in which nitrogen or sulfur atoms may optionally be oxidized, nitrogen atoms may optionally be quaternized, and one or more rings may be fully or partially saturated, or aromatic. A heterocyclyl or heterocyclic group may be attached to the main structure at any heteroatom or carbon atom which results in the creation of a stable compound. Examples of heterocyclyl or heterocyclic groups include without limitation azepinyl, azetidinyl, aziridinyl, benzodioxanyl, benzodioxolyl, benzofuranonyl, benzopyranonyl, benzopyranyl, benzotetrahydrofuranyl, benzotetrahydrothienyl, benzothiopyranyl, β-carbolinyl, chromanyl, decahydroisoquinolinyl, dihydrobenzisothiazinyl, dihydrobenzisoxazinyl, dihydrofuryl, dihydropyranyl, dihydropyrazinyl, dihydropyridinyl, dihydropyrazolyl, dihydropyrimidinyl, dihydropyrrolyl, dioxolanyl, dithianyl, furanonyl, imidazolidinyl, imidazolinyl, indolinyl, indolizinyl, isobenzotetrahydrofuranyl, isobenzotetrahydrothienyl, isochromanyl, isoindolinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, oxazolidinonyl, oxazolidinyl, oxiranyl, piperazinyl, piperidinyl, 4-piperidonyl, pyrrolidinyl, pyrrolinyl, quinuclidinyl, tetrahydrofuryl, tetrahydrofuranyl (oxolanyl), tetrahydroisoquinolinyl, tetrahydropyranyl, tetrahydrothienyl (tetrahydrothiophenyl, thiolanyl), thiamorpholinyl (thiomorpholinyl), thiazolidinyl and 1,3,5-trithianyl. The term “-heterocyclyl-” refers to a divalent heterocyclyl group. A heterocyclyl or heterocyclic group, and a -heterocyclyl- group, may optionally be substituted with one or more substituents as described herein.

The term “aryl” refers to a monocyclic aromatic hydrocarbon group or a multicyclic group that contains at least one aromatic hydrocarbon ring. In certain embodiments, an aryl group has from 6 to 15, or 6 to 12, or 6 to 10 ring atoms. Non-limiting examples of aryl groups include phenyl, naphthyl, fluorenyl, azulenyl, anthryl, phenanthryl, biphenyl and terphenyl. The aromatic hydrocarbon ring of an aryl group may be attached or fused to one or more saturated, partially unsaturated or aromatic rings—e.g., dihydronaphthyl, indenyl, indanyl and tetrahydronaphthyl (tetralinyl). The term “-aryl-” refers to a divalent aryl group. An aryl group and an -aryl- group may optionally be substituted with one or more substituents as described herein.

The term “heteroaryl” refers to a monocyclic aromatic group or a multicyclic group that contains at least one aromatic ring, wherein at least one aromatic ring contains one or more heteroatoms independently selected from O, N and S. The heteroaromatic ring may be attached or fused to one or more saturated, partially unsaturated or aromatic rings that may contain only carbon atoms or that may contain one or more heteroatoms. A heteroaryl group may be attached to the main structure at any heteroatom or carbon atom which results in the creation of a stable compound. In certain embodiments, a heteroaryl group has from 5 to 15, or 5 to 12, or 5 to 10 ring atoms. Examples of monocyclic heteroaryl groups include without limitation pyrrolyl, pyrazolyl, pyrazolinyl, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, thiadiazolyl, isothiazolyl, furanyl, thienyl (thiophenyl), oxadiazolyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl and triazinyl. Non-limiting examples of bicyclic heteroaryl groups include indolyl, benzothiazolyl, benzothiadiazolyl, benzoxazolyl, benzisoxazolyl, benzothienyl (benzothiophenyl), quinolinyl, tetrahydroisoquinolinyl, isoquinolinyl, benzimidazolyl, benzotriazolyl, indolizinyl, benzofuranyl, isobenzofuranyl, chromonyl, coumarinyl, cinnolinyl, quinazolinyl, quinoxalinyl, indazolyl, naphthyridinyl, phthalazinyl, quinazolinyl, purinyl, pyrrolopyridinyl, furopyridinyl, thienopyridinyl, dihydroisoindolyl and tetrahydroquinolinyl. Examples of tricyclic heteroaryl groups include without limitation carbazolyl, benzindolyl, dibenzofuranyl, phenanthrollinyl, acridinyl, phenanthridinyl and xanthenyl. The term “-heteroaryl-” refers to a divalent heteroaryl group. A heteroaryl group and a -heteroaryl- group may optionally be substituted with one or more substituents as described herein.

Each group described herein (including without limitation alkyl, heteroalkyl, haloalkyl, -alkylaryl, cycloalkyl, heterocyclyl, aryl and heteroaryl), whether as a primary group or as a substituent group, may optionally be substituted with one or more substituents. In certain embodiments, each group described herein may optionally be substituted with one to six substituents independently selected from the group consisting of halide, cyano, nitro, hydroxyl, sulfhydryl (—SH), amino (—NH₂), —OR¹¹, —SR¹¹, —NR¹²R¹³, —C(═O)R¹¹, —C(═O)OR¹¹, —OC(═O)R¹¹, —C(═O)NR¹²R¹³, —NR¹¹C(═O)R¹¹, alkyl, cycloalkyl, heterocyclyl, aryl and heteroaryl, wherein:

-   -   R¹¹ in each occurrence independently is hydrogen, alkyl,         cycloalkyl, heterocyclyl, aryl or heteroaryl; and     -   R¹² and R¹³ in each occurrence independently are hydrogen,         alkyl, cycloalkyl, heterocyclyl, aryl or heteroaryl, or R¹² and         R¹³ and the nitrogen atom to which they are connected form a         heterocyclic or heteroaryl ring.

II. STEREOISOMERS

It is understood that the present disclosure encompasses all possible stereoisomers, including all possible diastereomers and enantiomers and racemic mixtures of enantiomers, of the compounds described herein, and not only the specific stereoisomers as indicated by drawn structure or nomenclature. Some embodiments of the disclosure relate to the specific stereoisomers indicated by drawn structure or nomenclature. The specific recitation of the phrase “or stereoisomers thereof” or the like with respect to a compound in certain instances of the disclosure shall not be interpreted as an intended omission of any of the other possible stereoisomers of the compound in other instances of the disclosure where the term “compound” is used without recitation of the phrase “or stereoisomers thereof” or the like.

III. TREPROSTINIL DERIVATIVES

The present disclosure provides treprostinil derivatives that can function as prodrugs of treprostinil. In some embodiments, a treprostinil derivative is of Formula (I):

wherein:

-   -   R¹ and R² independently are hydrogen,

-   -    wherein:     -   R³ in each occurrence independently is alkyl, haloalkyl,         -alkylaryl, cycloalkyl, heterocyclyl, aryl or heteroaryl, each         of which may optionally be substituted;     -   R⁴ and R⁵ in each occurrence independently are hydrogen, C₁-C₆         alkyl or C₃-C₆ cycloalkyl, or R⁴ and R⁵ and the carbon atom to         which they are connected form a C₃-C₆ cycloalkyl ring;     -   R⁶ in each occurrence independently is hydrogen, R³, —C(═O)R³,         —C(═O)OR³ or —C(═O)NR⁹R¹⁰; or     -   R⁶ and R⁴ or R⁵, together with the atoms to which they are         connected, form a heterocyclic ring;     -   R⁹ and R¹⁰ in each occurrence independently are hydrogen, alkyl,         -alkylaryl, cycloalkyl, heterocyclyl, aryl or heteroaryl; or         -   R⁹ and R¹⁰ and the nitrogen atom to which they are connected             form a heterocyclic or heteroaryl ring;     -   j in each occurrence independently is an integer from 0 to 4;     -   m in each occurrence independently is an integer from 1 to 10;         and     -   t in each occurrence independently is an integer from 1 to 9;         or a pharmaceutically acceptable salt, solvate, hydrate,         clathrate, polymorph or stereoisomer thereof, with the proviso         that:

both R¹ and R² are not hydrogen;

neither —OR¹ nor —OR² forms an acetate;

neither —OR¹ nor —OR² forms a benzoate;

neither —OR¹ nor —OR² forms a substituted cyclohexane-ester;

neither —OR¹ nor —OR² forms an ester with or of an amino acid (protected or unprotected), a peptide or a protein; and

a compound of Formula (I) is not a homopolymer or heteropolymer of treprostinil, or does not contain more than one molecule or unit of treprostinil.

A treprostinil derivative of Formula (I) does not have either —OR¹ or —OR², or both, forming an ester with or of an amino acid (protected or unprotected), a peptide (e.g., a dipeptide, a tripeptide, a tetrapeptide or a longer peptide) or a protein. Furthermore, a compound of Formula (I) does not comprise treprostinil linked or conjugated to a peptide (including a polypeptide) or a protein. In addition, a compound of Formula (I) does not comprise treprostinil linked or conjugated to a polymer other than R and/or R² independently being

as described herein.

A compound of Formula (I) does not comprise treprostinil directly or indirectly attached to another molecule or monomer unit of treprostinil. In some embodiments, a compound of Formula (I) does not comprise treprostinil directly or indirectly attached to another therapeutic agent (e.g., a therapeutic agent containing at least one carboxyl group and at least one hydroxyl group). In certain embodiments, a compound of Formula (I) does not comprise treprostinil directly or indirectly attached to prostacyclin (also called prostaglandin 12 or epoprostenol) or an analog thereof (e.g., beraprost, cicaprost or iloprost), or to another prostaglandin or an analog thereof. In further embodiments, a compound of Formula (I) does not comprise treprostinil indirectly attached to another therapeutic agent via a linker containing a hydroxyl group and a carboxyl group (e.g., beta-hydroxybutyric acid, 6-hydroxyhexanoic acid, hydroxyl-polyethylene glycol-carboxylic acid, glycolic acid or lactic acid).

In certain embodiments, R³ in

is not alkyl substituted with a nitrogen-containing group, or not cycloalkyl substituted with a carbonyl-containing group. In further embodiments, neither the alkyl nor the cycloalkyl group of R³ in

is substituted. In yet further embodiments, none of the alkyl, haloalkl, -alkylaryl, cycloalkyl, heterocyclyl, aryl or heteroaryl group of R³ in

is substituted.

In additional embodiments, R³ in

is not either alkyl, unsubstituted alkyl or substituted alkyl. In some embodiments, R³ in

is not either haloalkyl, unsubstituted haloalkyl or substituted haloalkyl. In certain embodiments, R³ in

is not either -alkylaryl, unsubstituted -alkylaryl or substituted -alkylaryl. In further embodiments, R³ in

is not either cycloalkyl, unsubstituted cycloalkyl or substituted cycloalkyl. In other embodiments, R³ in

is not either heterocyclyl, unsubstituted heterocyclyl or substituted heterocyclyl. In yet other embodiments, R³ in

is not either aryl, unsubstituted aryl or substituted aryl. In still other embodiments, R³ in

is not either heteroaryl, unsubstituted heteroaryl or substituted heteroaryl.

In some embodiments, R³ in

is not either alkyl, unsubstituted alkyl or substituted alkyl. In certain embodiments, R³ in

is not either haloalkyl, unsubstituted haloalkyl or substituted haloalkyl. In further embodiments, R³ in

is not either -alkylaryl, unsubstituted -alkylaryl or substituted -alkylaryl. In additional embodiments, R³ in

is not either cycloalkyl, unsubstituted cycloalkyl or substituted cycloalkyl. In other embodiments, R³ in

is not either heterocyclyl, unsubstituted heterocyclyl or substituted heterocyclyl. In yet other embodiments, R³ in

is not either aryl, unsubstituted aryl or substituted aryl. In still other embodiments, R³ in

is not either heteroaryl, unsubstituted heteroaryl or substituted heteroaryl.

In certain embodiments, R⁶ in any one of

is not hydrogen. In some embodiments, R³ in the description of R⁶ in any one of

is not either alkyl, unsubstituted alkyl or substituted alkyl. In additional embodiments, R³ in the description of R⁶ in any one of

not either haloalkyl, unsubstituted haloalkyl or substituted haloalkyl. In further embodiments, R³ in the description of R⁶ in any one of

is not either -alkylaryl, unsubstituted -alkylaryl or substituted -alkylaryl. In still further embodiments, R³ in the description of R⁶ in any one of

not either cycloalkyl, unsubstituted cycloalkyl or substituted cycloalkyl. In other embodiments, R³ in the description of R⁶ in any one of

is not either heterocyclyl, unsubstituted heterocyclyl or substituted heterocyclyl. In yet other embodiments, R³ in the description of R⁶ in any one of

is not either aryl, unsubstituted aryl or substituted aryl. In still other embodiments, R³ in the description of R⁶ in any one of

and is not either heteroaryl, unsubstituted heteroaryl or substituted heteroaryl.

In some embodiments, j in each occurrence independently is 0, 1 or 2. In certain embodiments, j is 0. In further embodiments, m in each occurrence independently is an integer from 1 to 6, or from 1 to 3. In additional embodiments, t in each occurrence independently is an integer from 1 to 5, or from 1 to 3.

In some embodiments, R¹ and R² independently are hydrogen,

wherein R⁴, R⁵, R⁶ and m are as defined above, and k in each occurrence independently is an integer from 1 to 9, with the proviso that both R¹ and R² are not hydrogen. In certain embodiments, k in each occurrence independently is an integer from 1 to 5, or from 1 to 3.

In further embodiments, R³ in each occurrence independently is C₁-C₆ alkyl; R⁴ and R⁵ in each occurrence independently are hydrogen or C₁-C₃ alkyl, or R⁴ and R⁵ and the carbon atom to which they are connected form a cyclopropyl ring; R⁶ in each occurrence independently is hydrogen or R³; R⁹ and R¹⁰ in each occurrence independently are C₁-C₆ alkyl, or R⁹ and R¹⁰ and the nitrogen atom to which they are connected form a 3- to 6-membered heterocyclic ring; j in each occurrence independently is 0 or 1; m in each occurrence independently is 1 or 2; and t in each occurrence independently is 1 or 2. In certain embodiments, R³ in each occurrence independently is methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl or tert-butyl; R⁴ and R⁵ in each occurrence independently are hydrogen, methyl, ethyl, propyl or isopropyl; R⁶ in each occurrence independently is hydrogen or R³; R⁹ and R¹⁰ in each occurrence independently are C₁-C₃ alkyl; j is 0; m is 1; and t is 1.

In some embodiments, R¹ and R² independently are hydrogen or

with the proviso that both R¹ and R² are not hydrogen. In certain embodiments, R³ in each occurrence independently is C₂-C₆ alkyl, C₃-C₆ cycloalkyl, or 3- to 6-membered heterocyclyl. In some embodiments, R³ in each occurrence independently is C₂-C₆ alkyl.

In further embodiments, R¹ and R² independently are hydrogen or

with the proviso that both R¹ and R² are not hydrogen. In some embodiments, R⁴ and R⁵ in each occurrence are hydrogen with optional substitution of the alpha carbon atom (adjacent to the carbonyl group) with a C₁-C₃ alkyl group, R⁶ in each occurrence independently is hydrogen or C₁-C₆ alkyl, and m in each occurrence independently is an integer from 1 to 6 or from 1 to 3. In certain embodiments, R⁴ and R⁵ in each occurrence are hydrogen with optional substitution of the alpha carbon atom with a methyl group, R⁶ in each occurrence independently is hydrogen or C₁-C₃ alkyl (e.g., methyl), and m in each occurrence independently is an integer from 1 to 6 or from 1 to 3.

In still further embodiments, R¹ and R² independently are hydrogen,

with the proviso that both R¹ and R² are not hydrogen. In some embodiments, R⁴ and R⁵ in each occurrence are hydrogen, or R⁴ in each occurrence is hydrogen and R⁵ in each occurrence is C₁-C₃ alkyl; R⁶ in each occurrence independently is hydrogen or C₁-C₆ alkyl; and j in each occurrence independently is 0, 1 or 2. In certain embodiments, R⁴ and R⁵ in each occurrence are hydrogen, or R⁴ in each occurrence is hydrogen and R⁵ in each occurrence is methyl; R⁶ in each occurrence independently is hydrogen or C₁-C₃ alkyl (e.g., methyl); and j in each occurrence independently is 0 or 1.

In additional embodiments, R¹ and R² independently are hydrogen or

with the proviso that both R¹ and R² are not hydrogen. In some embodiments, R³ in each occurrence independently is C₁-C₆ alkyl or C₁-C₆ haloalkyl. In certain embodiments, R³ in each occurrence independently is C₁-C₃ alkyl or C₁-C₃ haloalkyl.

In other embodiments, R¹ and R² independently are hydrogen or

with the proviso that both R¹ and R² are not hydrogen. In some embodiments, R⁶ in each occurrence independently is hydrogen or C₁-C₆ alkyl, and t in each occurrence independently is an integer from 1 to 5 or from 1 to 3. In certain embodiments, R⁶ in each occurrence independently is hydrogen or C₁-C₃ alkyl (e.g., methyl), and t in each occurrence independently is an integer from 1 to 6 or from 1 to 3.

In yet other embodiments, R¹ and R² independently are hydrogen or

with the proviso that both R¹ and R² are not hydrogen. In some embodiments, R⁶ in each occurrence independently is hydrogen or C₁-C₆ alkyl, and j in each occurrence independently is 0, 1 or 2. In certain embodiments, R⁶ in each occurrence independently is hydrogen or C₁-C₃ alkyl (e.g., methyl), and j in each occurrence independently is 0 or 1.

In further embodiments, R¹ and R² independently are hydrogen or

with the proviso that both R¹ and R² are not hydrogen. In some embodiments, R⁹ and R¹⁰ in each occurrence independently are C₁-C₆ alkyl, or R⁹ and R¹⁰ and the nitrogen atom to which they are connected form a 3- to 6-membered heterocyclic ring, and t in each occurrence independently is an integer from 1 to 5 or from 1 to 3. In certain embodiments, R⁹ and R¹⁰ in each occurrence independently are C₁-C₃ alkyl (e.g., methyl), and t in each occurrence independently is an integer from 1 to 6 or from 1 to 3.

In additional embodiments, R¹ and R² independently are hydrogen,

with the proviso that both R¹ and R² are not hydrogen. In some embodiments, R⁶ in each occurrence independently is hydrogen or C₁-C₆ alkyl. In certain embodiments, R⁶ in each occurrence independently is C₁-C₃ alkyl (e.g., methyl).

In some embodiments, R and R² independently are selected from the group consisting of:

hydrogen,

wherein each moiety that has a stereocenter adjacent to the carbonyl group or anywhere else can have the (R)-stereochemistry or the (S)-stereochemistry or can be racemic at that stereocenter; with the proviso that both R¹ and R² are not hydrogen.

The disclosure specifically describes treprostinil derivatives in which: (1) R² is hydrogen and —OR¹ is derivatized with each of the moieties (other than hydrogen) in the preceding group; (2) R¹ is hydrogen and —OR² is derivatized with each of the moieties (other than hydrogen) in the preceding group; and (3) both —OR¹ and —OR² are derivatized with the same moiety and with each of the moieties (other than hydrogen) in the preceding group. In certain embodiments, R¹ and R² independently are selected from the group consisting of:

hydrogen,

with the proviso that both R¹ and R² are not hydrogen.

In some embodiments, both —OR¹ and —OR² are derivatized [Formula (Ic)], optionally with the same group. In other embodiments, R² is hydrogen and —OR¹ is derivatized [Formula (Ia)]. In yet other embodiments, R¹ is hydrogen and —OR² is derivatized [Formula (Ib)].

In certain embodiments, a treprostinil derivative of Formula (I) is selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof.

In other embodiments, a treprostinil derivative is of Formula (II):

wherein:

—O—Z—CO₂H is

—O-heteroalkyl-CO₂H, —O-cyclyl-CO₂H, —O—CH₂-cyclyl-CO₂H, —O-cyclyl-CH₂—CO₂H, or —O—CH₂-cyclyl-CH₂—CO₂H, each of which may optionally be substituted,

wherein:

-   -   -cyclyl- is -cycloalkyl-, -heterocyclyl-, -aryl- or         -heteroaryl-;     -   R⁷ and R⁸ in each occurrence independently are hydrogen, C₁-C₆         alkyl or C₃-C₆ cycloalkyl, or R⁷ and R⁸ and the carbon atom to         which they are connected form a C₃-C₆ cycloalkyl ring; and     -   n is an integer from 1 to 10;         or a pharmaceutically acceptable salt, solvate, hydrate,         clathrate, polymorph or stereoisomer thereof, with the proviso         that:

—O—Z—CO₂H is not

and

—O—Z—CO₂H does not contain a sugar moiety.

In some embodiments, n is an integer from 1 to 6, or from 1 to 3. In other embodiments, n is an integer from 3 to 10, or from 3 to 6. In further embodiments, each occurrence of R⁷ and R⁸ is hydrogen, and n is an integer from 1 to 10, or from 1 to 6, or from 1 to 3.

In certain embodiments, —O—Z—CO₂H is not

In further embodiments, each occurrence of R⁷ and R⁸ is hydrogen when n is 1 or 2.

In some embodiments, —O—Z—CO₂H does not contain a -heterocyclyl- group, or a substituted -heterocyclyl- group.

In additional embodiments, -cyclyl- in either —O-cyclyl-CO₂H, —O—CH₂-cyclyl-CO₂H, —O— cyclyl-CH₂—CO₂H or —O—CH₂-cyclyl-CH₂—CO₂H is not either -cycloalkyl-, unsubstituted -cycloalkyl- or substituted -cycloalkyl-. In other embodiments, -cyclyl- in either —O-cyclyl-CO₂H, —O—CH₂-cyclyl-CO₂H, —O-cyclyl-CH₂—CO₂H or —O—CH₂-cyclyl-CH₂—CO₂H is not either -heterocyclyl-, unsubstituted -heterocyclyl- or substituted -heterocyclyl-. In still other embodiments, -cyclyl- in either —O-cyclyl-CO₂H, —O—CH₂-cyclyl-CO₂H, —O-cyclyl-CH₂—CO₂H or —O—CH₂-cyclyl-CH₂—CO₂H is not either -aryl-, unsubstituted -aryl- or substituted -aryl-. In yet other embodiments, -cyclyl- in either —O-cyclyl-CO₂H, —O—CH₂-cyclyl-CO₂H, —O-cyclyl-CH₂—CO₂H or —O—CH₂-cyclyl-CH₂—CO₂H is not either -heteroaryl-, unsubstituted -heteroaryl- or substituted -heteroaryl-.

In some embodiments, —O—Z—CO₂H is

with the proviso that —O—Z—CO₂H is not

In certain embodiments, R⁷ and R⁸ in each occurrence are hydrogen with optional substitution of the carbon atom adjacent to the ester oxygen atom with a C₁-C₆ alkyl group, and n is an integer from 1 to 6 or from 1 to 3. In some embodiments, R⁷ and R⁸ in each occurrence are hydrogen with optional substitution of the carbon atom adjacent to the ester oxygen atom with a C₁-C₃ alkyl (e.g., methyl) group, and n is an integer from 1 to 6 or from 1 to 3.

In further embodiments, —O—Z—CO₂H is

wherein R⁷ and R⁸ are as defined above, p is an integer from 1 to 9, and q is an integer from 0 to 8, with the proviso that —O—Z—CO₂H is not

In certain embodiments, p is an integer from 1 to 5 or from 1 to 3, and q is an integer from 0 to 4 or from 0 to 2. In some embodiments, both R⁷ and R⁸ are hydrogen, and p is an integer from 1 to 5 or from 1 to 3 (or each occurrence of R⁷ and R⁸ is hydrogen, and q is an integer from 0 to 4 or from 0 to 2). The disclosure specifically describes treprostinil derivatives in which both R⁷ and R⁸ are hydrogen, and p is each of 1, 2, 3, 4, 5, 6, 7, 8 and 9. In further embodiments, —O—Z—CO₂H is

and p is 2, 3, 4 or 5. The disclosure specifically describes treprostinil derivatives in which —O—Z—CO₂H is

and p is each of 2, 3, 4, 5, 6, 7, 8 and 9, wherein the stereocenter connected to the methyl group can have the (R)-stereochemistry or the (S)-stereochemistry or can be racemic at that position.

In additional embodiments, —O—Z—CO₂H is

wherein ring A is cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl, and u is an integer from 0 to 9. The disclosure specifically describes treprostinil derivatives in which ring A is each of cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl, and u is each of 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. In certain embodiments, —O—Z—CO₂H is

wherein u is an integer from 0 to 9 or from 0 to 5. Again, the disclosure specifically describes treprostinil derivatives in which —O—Z—CO₂H is

and u and u is each of 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.

In other embodiments, —O—Z—CO₂H is —O-heteroalkyl-CO₂H, and —O-heteroalkyl-CO₂H is selected from the group consisting of:

wherein r is each of 1, 2 and 3; and

wherein each moiety that has a stereocenter adjacent to the oxygen atom connected to treprostinil, and/or a stereocenter adjacent to the carboxyl group, independently can have the (R)-stereochemistry or the (S)-stereochemistry or can be racemic at that (those) stereocenter(s). The disclosure specifically describes treprostinil derivatives in which —O—Z—CO₂H is each of the moieties in the preceding group. In certain embodiments, —O—Z—CO₂H is

wherein r is 1, 2 or 3.

In further embodiments, —O—Z—CO₂H is —O-cycloalkyl-CO₂H, —O—CH₂-cycloalkyl-CO₂H, —O-cycloalkyl-CH₂—CO₂H, or —O—CH₂-cycloalkyl-CH₂—CO₂H, and for each of the preceding moieties -cycloalkyl- is:

1,2-cyclopropyl (cis or trans); or

1,3-cyclobutyl (cis or trans) or 1,2-cyclobutyl (cis or trans); or

1,3-cyclopentyl (cis or trans) or 1,2-cyclopentyl (cis or trans); or

1,4-cyclohexyl (cis or trans), 1,3-cyclohexyl (cis or trans), or 1,2-cyclohexyl (cis or trans).

The disclosure specifically describes the 64 treprostinil derivatives in which —O—Z—CO₂H is each of the moieties in the preceding group. In certain embodiments, —O—Z—CO₂H is selected from the group consisting of:

wherein for each of the moieties the two groups on the cycloalkyl ring can be cis or trans relative to one another.

In some embodiments, a treprostinil derivative of Formula (II) is selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof.

The treprostinil derivatives described herein can exist or be used in the form of a pharmaceutically acceptable salt. The treprostinil derivatives have a carboxyl group, and thus can form an addition salt with a base. Pharmaceutically acceptable base addition salts can be formed with, e.g., metals (e.g., alkali metals or alkaline earth metals) or amines (e.g., organic amines). Examples of metals useful as cations include without limitation alkali metals (e.g., lithium, sodium, potassium and cesium), alkaline earth metals (e.g., magnesium, calcium and barium), aluminum and zinc. Metal cations can be provided by way of, e.g., inorganic bases, such as hydroxides, carbonates and hydrogen carbonates. Non-limiting examples of organic amines useful for forming base addition salts include chloroprocaine, choline, cyclohexylamine, dibenzylamine, N,N′-dibenzylethylene-diamine, dicyclohexylamine, diethanolamine, ethylenediamine, N-ethylpiperidine, histidine, isopropylamine, N-methylglucamine, procaine, pyrazine, triethylamine, trimethylamine and tromethamine.

If a compound has a basic atom or functional group (e.g., a basic nitrogen atom), the compound can form an addition salt with an acid. Non-limiting examples of acids useful for forming acid addition salts include mineral acids (e.g., HCl, HBr, HI, nitric acid, phosphoric acid and sulfuric acid) and organic acids, such as carboxylic acids (e.g., acetic acid) and sulfonic acids (e.g., ethanesulfonic acid). Pharmaceutically acceptable salts are discussed in detail in Handbook of Pharmaceutical Salts, Properties, Selection and Use, P. Stahl and C. Wermuth, Eds., Wiley-VCH (2011).

IV. DEUTERATED TREPROSTINIL COMPOUNDS

To eliminate foreign substances such as drugs, the animal body expresses a variety of enzymes, such as cytochrome P₄₅₀ enzymes, esterases, proteases, reductases, dehydrogenases and monoamine oxidases, which react with and convert the foreign substances to more polar intermediates or metabolites for renal excretion. Such metabolic reactions can involve the oxidation of a carbon-hydrogen (C—H) bond to a carbon-oxygen (C—O) bond or a carbon-carbon (C═C) pi bond. The resulting metabolites may be stable or unstable under physiological conditions, and may have substantially different pharmacologic, pharmacokinetic and pharmacodynamic properties and toxicity profiles compared to the parent compounds. For many drugs, such metabolic oxidations can be rapid and lead to the requirement of higher dosage amounts and/or increased dosing frequencies, which can result in greater side effects.

The present disclosure provides treprostinil isotopologues corresponding to the treprostinil derivatives described herein which are enriched with deuterium (deuterated) at one or more positions. In some embodiments, a treprostinil derivative is deuterated at one or more positions in the parent treprostinil structure so that when the derivative is converted to treprostinil in vivo, the resulting active parent drug is deuterated at one or more positions.

Deuteration of a treprostinil compound at one or more positions can have any one or more, or all, of the following benefits: (1) a longer half-life; (2) decreased amount of a dose and/or decreased number of doses needed to achieve a desired effect; (3) decreased variation between subjects in the blood or plasma level of the parent drug; (4) increased efficacy; (5) reduced side effects due to decreased amount of the parent drug administered and/or decreased production of deleterious metabolites; and (6) increased maximum tolerated dose.

Deuterium can be substituted for hydrogen at any one or more, or all, of the available positions in a treprostinil (Trp) compound, including at any one or more, or all, of the available positions in the phenyl ring of Trp, the cyclohexyl ring of Trp, the cyclopentyl ring of Trp, the octyl chain of Trp, or the hydroxyacetic acid group of Trp, or any combination thereof. In certain embodiments, a treprostinil derivative is deuterated at one or more, or all, of the available positions in the cyclohexyl ring of Trp and/or the hydroxyacetic acid group of Trp. In some embodiments, at least one of the available positions has deuterium enrichment of at least about 10%, 25%, 50%, 75%, 90%, 95% or 98%. In certain embodiments, at least one of the available positions has deuterium enrichment of at least about 90%, 95% or 98%.

In further embodiments, each position in a treprostinil derivative enriched with deuterium (or deuterated) independently has deuterium enrichment of at least about 10%, 25%, 50%, 75%, 90%, 95% or 98%. In certain embodiments, each position enriched with deuterium independently has deuterium enrichment of at least about 90%, 95% or 98%.

Deuterated treprostinil derivatives can also contain less prevalent isotopes for other elements, including without limitation ¹³C or ¹⁴C for carbon and ¹⁷O or ¹⁸O for oxygen.

The term “deuterium enrichment” refers to the percentage of incorporation of deuterium at a given position in a molecule in place of hydrogen. For example, deuterium enrichment of 10% at a given position means that 10% of molecules in a given sample contain deuterium at that position. Because the naturally occurring distribution of deuterium is about 0.0156%, deuterium enrichment at any position in a molecule synthesized using non-deuterium-enriched starting materials or reagents is about 0.0156%. Deuterium enrichment can be determined using conventional analytical methods known to one of ordinary skill in the art, including mass spectrometry and nuclear magnetic resonance spectroscopy.

The term “is deuterium” or “is deuterated”, when used to describe a given position in a molecule, or the symbol “D”, when used to represent an element at a given position in a drawing of a molecular structure, means that the specified position is enriched with deuterium above the naturally occurring distribution of deuterium. In some embodiments, deuterium enrichment is at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98% or 99% (e.g., at least about 50%) of deuterium at the specified position. In certain embodiments, deuterium enrichment is at least about 90%, 95% or 98% of deuterium at the specified position.

V. PHARMACEUTICAL COMPOSITIONS

Additional embodiments of the disclosure relate to pharmaceutical compositions comprising one or more treprostinil derivatives described herein, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate or polymorph thereof, and one or more pharmaceutically acceptable excipients or carriers. The compositions can optionally contain an additional therapeutic agent.

Pharmaceutically acceptable excipients and carriers include pharmaceutically acceptable substances, materials and vehicles. Non-limiting examples of excipients include liquid and solid fillers, diluents, binders, lubricants, glidants, surfactants, dispersing agents, disintegration agents, emulsifying agents, wetting agents, suspending agents, thickeners, solvents, isotonic agents, buffers, pH adjusters, absorption-delaying agents, sweetening agents, flavoring agents, coloring agents, stabilizers, preservatives, antioxidants, antimicrobial agents, antibacterial agents, antifungal agents, adjuvants, encapsulating materials and coating materials. The use of such excipients in pharmaceutical formulations is known in the art. For example, conventional vehicles and carriers include without limitation oils (e.g., vegetable oils, such as sesame oil), aqueous solvents (e.g., saline and phosphate-buffered saline [PBS]), and solvents (e.g., dimethyl sulfoxide [DMSO] and alcohols [such as ethanol and glycerol]). Except insofar as any conventional excipient or carrier is incompatible with the active ingredient (for purposes of the content of a pharmaceutical composition, the term “active ingredient” encompasses a prodrug), the disclosure encompasses the use of conventional excipients and carriers in formulations containing treprostinil derivatives. See, e.g., Remington: The Science and Practice of Pharmacy, 21st Ed., Lippincott Williams & Wilkins (Philadelphia, Pa. [2005]); Handbook of Pharmaceutical Excipients, 5th Ed., Rowe et al., Eds., The Pharmaceutical Press and the American Pharmaceutical Association (2005); Handbook of Pharmaceutical Additives, 3rd Ed., Ash and Ash, Eds., Gower Publishing Co. (2007); and Pharmaceutical Pre-formulation and Formulation, Gibson, Ed., CRC Press LLC (Boca Raton, Fla. [2004]).

Proper formulation can depend on various factors, such as the route of administration chosen. Potential routes of administration of pharmaceutical compositions comprising treprostinil derivatives include without limitation oral, parenteral (including intradermal, subcutaneous, intramuscular, intravascular, intravenous, intraarterial, intramedullary and intrathecal), intracavitary, intraperitoneal, and topical (including dermal/epicutaneous, transdermal, mucosal, transmucosal, intranasal [e.g., by nasal spray or drop], intraocular [e.g., by eye drop], pulmonary [e.g., by inhalation], buccal, sublingual, rectal and vaginal). Topical formulations can be designed to produce a local or systemic therapeutic effect.

As an example, formulations of treprostinil derivatives suitable for oral administration can be presented as, e.g., capsules (including push-fit capsules and soft capsules), cachets or tablets; as powders or granules; or as boluses, electuaries or pastes. For example, push-fit capsules can contain a treprostinil derivative in admixture with, e.g., a filler (e.g., lactose), a binder (e.g., a starch) and a lubricant (e.g., talc or magnesium stearate), and optionally a stabilizer. For soft capsules, a treprostinil derivative can be dissolved or suspended in a suitable liquid (e.g., a fatty oil, liquid paraffin or liquid polyethylene glycol), and a stabilizer can be added.

Compositions for oral administration can also be formulated as solutions or suspensions in an aqueous liquid and/or a non-aqueous liquid, or as oil-in-water liquid emulsions or water-in-oil liquid emulsions. Dispersible powder or granules of a treprostinil derivative can be mixed with any suitable combination of an aqueous liquid, an organic solvent and/or an oil and any suitable excipients (e.g., any combination of a dispersing agent, a wetting agent, a suspending agent, an emulsifying agent and/or a preservative) to form a solution, suspension or emulsion.

Treprostinil derivatives can also be formulated for parenteral administration by injection or infusion to circumvent gastrointestinal absorption and first-pass metabolism. An exemplary parenteral route is intravenous. Additional advantages of intravenous administration include direct administration of a therapeutic agent into systemic circulation to achieve a rapid systemic effect, and the ability to administer the agent continuously and/or in a large volume if desired. Formulations for injection or infusion can be in the form of, e.g., solutions, suspensions or emulsions in oily or aqueous vehicles, and can contain excipients such as suspending agents, dispersing agents and/or stabilizing agents. For example, aqueous or non-aqueous (e.g., oily) sterile injection solutions can contain a treprostinil derivative along with excipients such as an antioxidant, a buffer, a bacteriostat and solutes that render the formulation isotonic with the blood of the subject. Aqueous or non-aqueous sterile suspensions can contain a treprostinil derivative along with excipients such as a suspending agent and a thickening agent, and optionally a stabilizer and an agent that increases the solubility of the treprostinil derivative to allow for the preparation of a more concentrated solution or suspension. As another example, a sterile aqueous solution for injection or infusion (e.g., subcutaneously or intravenously) can contain a treprostinil derivative, sodium chloride, a buffering agent (e.g., sodium citrate), a preservative (e.g., meta-cresol), and optionally a base (e.g., NaOH) and/or an acid (e.g., HCl) to adjust pH.

In some embodiments, a topical dosage form of a treprostinil derivative is formulated as a buccal or sublingual tablet or pill. Advantages of a buccal or sublingual tablet or pill include avoidance of gastrointestinal absorption and first-pass metabolism, and rapid absorption into systemic circulation. A buccal or sublingual tablet or pill can be designed to provide faster release of the treprostinil derivative for more rapid uptake of it into systemic circulation. In addition to a therapeutically effective amount of a treprostinil derivative, the buccal or sublingual tablet or pill can contain suitable excipients, including without limitation any combination of fillers and diluents (e.g., mannitol and sorbitol), binding agents (e.g., sodium carbonate), wetting agents (e.g., sodium carbonate), disintegrants (e.g., crospovidone and croscarmellose sodium), lubricants (e.g., silicon dioxide [including colloidal silicon dioxide] and sodium stearyl fumarate), stabilizers (e.g., sodium bicarbonate), flavoring agents (e.g., spearmint flavor), sweetening agents (e.g., sucralose), and coloring agents (e.g., yellow iron oxide).

In addition, treprostinil derivatives can be formulated for intranasal administration. Intranasal administration bypasses gastrointestinal absorption and first-pass metabolism. An intranasal formulation can comprise a treprostinil derivative along with excipients, such as a solubility enhancer (e.g., propylene glycol), a humectant (e.g., mannitol or sorbitol), a buffer and water, and optionally a preservative (e.g., benzalkonium chloride), a mucoadhesive agent (e.g., hydroxyethylcellulose) and/or a penetration enhancer.

Furthermore, treprostinil derivatives can be formulated for administration by oral inhalation. Advantages of administration by inhalation include avoidance of first-pass metabolism, and the ability to tailor to rapid delivery of the therapeutic agent across the mucous membrane of the respiratory tract, or more selective deposition of the agent in the lungs with less systemic side effects. In certain embodiments, a sterile aqueous solution for oral inhalation contains a treprostinil derivative, sodium chloride, a buffering agent (e.g., sodium citrate), optionally a preservative (e.g., meta-cresol), and optionally a base (e.g., NaOH) and/or an acid (e.g., HCl) to adjust pH.

For a delayed or sustained release of a treprostinil derivative, a composition can be formulated as, e.g., a depot that can be implanted in or injected into a subject, e.g., intramuscularly or subcutaneously. A depot formulation can be designed to deliver the treprostinil derivative over an extended period of time, e.g., over at least about 1 week, 2 weeks, 3 weeks, 1 month, 1.5 months, 2 months or longer. For example, a treprostinil derivative can be formulated with a polymeric material (e.g., polyethylene glycol [PEG], polylactic acid [PLA] or polyglycolic acid [PGA], or a copolymer thereof [e.g., PLGA]), a hydrophobic material (e.g., as an emulsion in an oil) and/or an ion-exchange resin, or as a sparingly soluble derivative (e.g., a sparingly soluble salt). As an illustrative example, a treprostinil derivative can be incorporated or embedded in sustained-release microparticles composed of PLGA and formulated as a monthly depot.

A treprostinil derivative can also be contained or dispersed in a matrix material. The matrix material can comprise a polymer (e.g., ethylene-vinyl acetate) and controls the release of the compound by controlling dissolution and/or diffusion of the compound from, e.g., a reservoir, and can enhance the stability of the compound while contained in the reservoir. Such a “release system” can be configured as a transdermal or transmucosal patch and can contain an excipient that can accelerate the compound's release, such as a water-swellable material (e.g., a hydrogel) that aids in expelling the compound out of the reservoir. U.S. Pat. Nos. 4,144,317 and 5,797,898 describe examples of such a release system.

The release system can provide a temporally modulated release profile (e.g., pulsatile release) when time variation in plasma levels is desired, or a more continuous or consistent release profile when a constant plasma level is desired. Pulsatile release can be achieved from an individual reservoir or from a plurality of reservoirs. For example, where each reservoir provides a single pulse, multiple pulses (“pulsatile” release) are achieved by temporally staggering the single pulse release from each of multiple reservoirs. Alternatively, multiple pulses can be achieved from a single reservoir by incorporating several layers of a release system and other materials into a single reservoir. Continuous release can be achieved by incorporating a release system that degrades, dissolves, or allows diffusion of a compound through it over an extended time period. In addition, continuous release can be approximated by releasing several pulses of a compound in rapid succession (“digital” release). An active release system can be used alone or in conjunction with a passive release system, as described in U.S. Pat. No. 5,797,898.

The pharmaceutical compositions can be manufactured in any suitable manner known in the art, e.g., by means of conventional mixing, dissolving, suspending, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping or compressing processes.

The compositions can be presented in unit dosage form as a single dose wherein all active and inactive ingredients are combined in a suitable system, and components do not need to be mixed to form the composition to be administered. The unit dosage form can contain an effective dose, or an appropriate fraction thereof, of a treprostinil derivative. A representative example of a unit dosage form is a tablet, capsule, or pill for oral uptake.

Alternatively, the compositions can be presented as a kit, wherein the active ingredient, excipients and carriers (e.g., solvents) are provided in two or more separate containers (e.g., ampules, vials, tubes, bottles or syringes) and need to be combined to form the composition to be administered. The kit can contain instructions for storing, preparing and administering the composition (e.g., a solution to be injected intravenously).

In some embodiments, a kit contains a treprostinil derivative or a pharmaceutically acceptable salt, solvate, hydrate, clathrate or polymorph thereof, and instructions for administering the compound to treat a condition responsive to treatment with treprostinil (e.g., pulmonary hypertension, such as pulmonary arterial hypertension). In certain embodiments, the compound is contained or incorporated in, or provided by, a device or system configured for transdermal delivery of the compound (e.g., a transdermal patch).

VI. TOPICAL COMPOSITIONS, INCLUDING TRANSDERMAL DELIVERY SYSTEMS

Topical formulations for application to the skin or mucosa can be useful for transdermal or transmucosal administration of a therapeutic agent into the blood for systemic distribution. Advantages of topical administration can include circumvention of gastrointestinal absorption and first-pass metabolism, delivery of a therapeutic agent with a short half-life and low oral bioavailability, more controlled and sustained release of the therapeutic agent, a more uniform plasma dosing or delivery profile of the therapeutic agent, less frequent dosing of the therapeutic agent, minimal or no invasiveness, ease of self-administration, and increased patient compliance. For purposes of the content of a pharmaceutical composition, the term “therapeutic agent” or “drug” encompasses a prodrug.

In general and in addition to the disclosure on topical formulations described elsewhere herein, compositions suitable for topical administration include without limitation liquid or semi-liquid preparations such as sprays, gels, liniments, lotions, oil-in-water or water-in-oil emulsions such as creams, foams, ointments and pastes, and solutions or suspensions such as drops (e.g., eye drops, nose drops and ear drops). In some embodiments, a topical composition comprises a therapeutic agent dissolved, dispersed or suspended in a carrier. The carrier can be in the form of, e.g., a solution, a suspension, an emulsion, an ointment or a gel base, and can contain, e.g., petrolatum, lanolin, a wax (e.g., bee wax), mineral oil, a long-chain alcohol, polyethylene glycol or polypropylene glycol, a diluent (e.g., water and/or an alcohol [e.g., ethanol or propylene glycol]), an emulsifier, a stabilizer or a thickening agent, or any combination thereof. A topical composition can include, or a topical formulation can be administered by means of, e.g., a transdermal or transmucosal delivery device, such as a transdermal patch, a microneedle patch or an iontophoresis device. A topical composition can deliver a drug transdermally or transmucosally via a concentration gradient (with or without the use of a chemical permeation enhancer) or an active mechanism (e.g., iontophoresis or microneedles).

In some embodiments, the treprostinil derivatives described herein are administered transdermally. In certain embodiments, the topical composition (e.g., transdermal delivery system) comprises a chemical permeation enhancer (e.g., a surfactant [e.g., sodium laureth sulfate], optionally in combination with an aromatic compound [e.g., phenylpiperazine]) that facilitates the transport of a treprostinil derivative across the skin into systemic circulation. In further embodiments, the treprostinil derivatives are administered via a transdermal patch. In certain embodiments, a transdermal patch comprises an impermeable backing membrane or layer, a drug reservoir, a semi-permeable membrane that can serve as a rate-limiting or rate-controlling diffusion barrier, and a skin-contacting adhesive layer. The semi-permeable membrane can be composed of, e.g., a suitable polymeric material (e.g., cellulose nitrate or acetate, polyisobutene, polypropylene, polyvinyl acetate or a polycarbonate). Transdermal drug-delivery systems, including patches, can be designed to provide controlled and prolonged release of a drug up to, e.g., about 1 week or longer. WO 1993/003696 and U.S. Pat. Nos. 3,598,122; 4,144,317; 4,201,211; 4,262,003 and 4,379,454 describe various transdermal drug-delivery systems, including patches, which can deliver a controlled amount of a drug for an extended period of time ranging from several hours to several days. Such systems may be adapted for transdermal delivery of treprostinil derivatives.

VII. THERAPEUTIC USES OF TREPROSTINIL DERIVATIVES

The treprostinil derivatives described herein can be converted to treprostinil in vivo, and thus can act as prodrugs of treprostinil. In some embodiments, treprostinil derivatives are converted to treprostinil slowly and to an insubstantial extent (e.g., less than about 30%, 20%, 10% or 5% conversion) in the blood or the skin (if administered, e.g., transdermally), and are converted to treprostinil rapidly and substantially completely (e.g., at least about 70%, 80%, 90% or 95% conversion) in the liver. In other embodiments, treprostinil derivatives are converted to treprostinil to a substantial extent (e.g., at least about 30%, 40%, 50% or 60% conversion), or substantially completely (e.g., at least about 70%, 80%, 90% or 95% conversion), in the blood. In yet other embodiments, treprostinil derivatives are administered transdermally, are converted to treprostinil to some extent (e.g., less than about 30%, 20% or 10% conversion) in the skin, and do not cause a significant amount of side effects in the area of administration, such as irritation. In further embodiments, the treprostinil derivatives are at least about 50-fold, 100-fold, 500-fold or 1000-fold (e.g., at least about 100-fold) less effective in agonizing the prostacyclin receptor than treprostinil.

Treprostinil, a prostacyclin (prostaglandin I₂) analog, has a variety of prostacyclin-like effects. For example, treprostinil can promote vasodilation, inhibit platelet activation and aggregation, inhibit thrombus formation, stimulate thrombolysis, inhibit atherogenesis, inhibit cell proliferation, inhibit angiogenesis, promote endothelial cell membrane remodeling, reduce inflammation, and provide cytoprotection. As prodrugs of treprostinil, the treprostinil derivatives described herein can be used to treat a wide variety of conditions, including without limitation: pulmonary hypertension, portopulmonary hypertension, pulmonary fibrosis, interstitial lung disease, ischemic diseases (e.g., myocardial ischemia, ischemic stroke, peripheral vascular disease [including peripheral arterial disease], ischemia of a limb, Raynaud's phenomenon [including Raynaud's disease and Raynaud's syndrome], scleroderma [including systemic sclerosis] and renal insufficiency), ischemic ulcers (e.g., digital ulcers), cardiovascular disease (e.g., coronary artery disease), heart failure (e.g., congestive heart failure), conditions requiring anticoagulation (e.g., post myocardial infarction and post cardiac surgery), atherogenesis (e.g., atherosclerosis), thrombotic microangiopathy, vein occlusion (e.g., central retinal vein occlusion), hypertension (e.g., preeclampsia), diabetic vasculopathy, extracorporeal circulation, inflammatory diseases (e.g., chronic obstructive pulmonary disease [COPD] and psoriasis), reproduction and parturition, conditions of unregulated cell growth (e.g., tumors and cancers), cell/tissue preservation, and other therapeutic areas where prostacyclin or treprostinil treatment may provide benefit.

In some embodiments, one or more treprostinil derivatives, or pharmaceutically acceptable salts, solvates, hydrates, clathrates or polymorphs thereof, are used to treat a prostacyclin- or treprostinil-responsive condition selected from the group consisting of pulmonary hypertension, pulmonary fibrosis, interstitial lung disease, asthma, congestive heart failure, peripheral vascular disease, severe intermittent claudication, atherogenesis (e.g., atherosclerosis), ischemic lesions (e.g., peripheral ischemic lesions on the skin, such as those caused by Buerger's disease, Raynaud's phenomenon, Raynaud's disease, scleroderma and systemic sclerosis), critical limb ischemia, neuropathic foot ulcers (e.g., diabetic neuropathic foot ulcer), kidney malfunction and failure, immunosuppression, proliferative disorders (e.g., tumors and cancers, such as those of the head and neck, brain, lung, liver, kidney, pancreas, gastrointestinal tract [e.g., colon], prostate and breast), and pain associated with each of the preceding conditions.

A treprostinil derivative can be used in conjunction with an additional therapeutic agent to treat any condition responsive to treatment with prostacyclin or treprostinil. As a non-limiting example, to treat a vascular (e.g., cardiovascular) disorder a treprostinil derivative can be used in combination with a vascular (e.g., cardiovascular) therapeutic, such as an antiplatelet agent, a phosphodiesterase inhibitor, a calcium channel blocker or an endothelial antagonist, or any combination thereof.

In some embodiments, the treprostinil derivatives described herein are used to treat pulmonary hypertension. An additional therapeutic agent (e.g., a vasoactive agent, a diuretic, an anticoagulant or a cardiac glycoside, or any combination thereof) can optionally be administered to treat pulmonary hypertension. In certain embodiments, the pulmonary hypertension is pulmonary arterial hypertension.

Pulmonary hypertension is an increase of blood pressure in the lung vasculature, including the pulmonary artery, pulmonary vein and pulmonary capillaries. Thus, pulmonary hypertension encompasses pulmonary arterial hypertension (PAH) and pulmonary venous hypertension (PVH) (e.g., congestive heart failure). More broadly, pulmonary hypertension encompasses:

WHO Group I—pulmonary arterial hypertension, including idiopathic PAH, heritable PAH (e.g., BMPR2, ALK1 and endoglin [with or without hereditary hemorrhagic telangiectasia]), drug- and toxin-induced PAH, PAH associated with various conditions (e.g., connective tissue disease, HIV infection, portal hypertension, congenital heart disease, schistosomiasis, and chronic hemolytic anemia [e.g., sickle cell disease]), persistent pulmonary hypertension of the newborn, pulmonary veno-occlusive disease (PVOD), and pulmonary capillary hemangiomatosis (PCH);

WHO Group II—pulmonary hypertension owing to left heart disease, including systolic dysfunction, diastolic dysfunction and valvular heart disease;

WHO Group III—pulmonary hypertension owing to lung disease and/or hypoxia, including chronic obstructive pulmonary disease (COPD), interstitial lung disease, other pulmonary diseases with mixed restrictive and obstructive pattern, sleep-disordered breathing, alveolar hypoventilation disorders, chronic exposure to high altitude, and developmental abnormalities;

WHO Group IV—chronic thromboembolic pulmonary hypertension (CTEPH); and

WHO Group V—pulmonary hypertension with unclear multifactorial mechanisms, including hematologic diseases (e.g., myeloproliferative disease and splenectomy), systemic diseases (e.g., sarcoidosis, pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, neurofibromatosis and vasculitis), metabolic disorders (e.g., glycogen storage disease, Gaucher disease and thyroid diseases), and other causes (e.g., tumoral obstruction, fibrosing mediastinitis and chronic renal failure on dialysis).

The therapeutically effective amount and frequency of administration of a treprostinil derivative to treat, e.g., pulmonary hypertension may depend on various factors, including the type of pulmonary hypertension, the severity of the condition, the mode of administration, the age, body weight, general health, gender and diet of the subject, and the response of the subject to the treatment, and can be determined by the treating physician. In certain embodiments, the effective dose of a treprostinil derivative per day is about 0.1-100 mg, 0.1-50 mg, 0.5-50 mg, 0.5-25 mg, 0.5-10 mg, 1-10 mg or 1-5 mg, or as deemed appropriate by the treating physician, which can be administered in a single dose or in divided doses. In further embodiments, the effective dose of a treprostinil derivative per day is about 0.001-2 mg/kg, 0.005-1 mg/kg, 0.01-0.5 mg/kg or 0.01-0.1 mg/kg body weight, or as deemed appropriate by the treating physician.

In some embodiments, a treprostinil derivative is administered, in a single dose or in multiple doses, daily (including one, two, three or more times daily), every two days, every three days, weekly, every 2 weeks, every 3 weeks, monthly, every 6 weeks, every 2 months or every 3 months, or as deemed appropriate by the treating physician. In certain embodiments, a treprostinil derivative is administered over a period of at least about 1 week, 2 weeks or 3 weeks. In further embodiments, a treprostinil derivative is administered under a chronic dosing regimen. In certain embodiments, a therapeutically effective amount of a treprostinil derivative is administered over a period of at least about 1 month, 1.5 months, 2 months, 3 months, 4 months, 5 months, 6 months, 1 year or longer.

A treprostinil derivative can be administered via any suitable route. Potential routes of administration of a treprostinil derivative include without limitation oral, parenteral (including intradermal, subcutaneous, intramuscular, intravascular, intravenous, intraarterial, intramedullary and intrathecal), intracavitary, intraperitoneal, and topical (including dermal/epicutaneous, transdermal, mucosal, transmucosal, intranasal [e.g., by nasal spray or drop], intraocular [e.g., by eye drop], pulmonary [e.g., by inhalation], buccal, sublingual, rectal and vaginal). In some embodiments, a treprostinil derivative is administered topically (e.g. dermally, transdermally, mucosally, transmucosally, intranasally, pulmonarily [e.g., by inhalation], or sublingually). In certain embodiments, a treprostinil derivative is administered transdermally (e.g., via a transdermal patch). In other embodiments, a treprostinil derivative is administered by inhalation (e.g., oral inhalation). In further embodiments, a treprostinil derivative is administered orally. In additional embodiments, a treprostinil derivative is administered parenterally (e.g., subcutaneously or intravenously, including by injection or infusion).

In some embodiments, a treprostinil derivative is used to treat PAH. In certain embodiments, the treprostinil derivative is administered transdermally, e.g., via a transdermal patch. In further embodiments, an additional therapeutic agent is administered in combination with the treprostinil derivative to treat PAH. The additional therapeutic agent can be administered concurrently with or sequentially to (before or after) administration of the treprostinil derivative. If administered concurrently with the treprostinil derivative, the additional therapeutic agent can be contained in the same composition as the treprostinil derivative or in separate compositions.

In certain embodiments, the additional therapeutic agent for the treatment of PAH is selected from the group consisting of:

vasoactive (e.g., vasodilating) agents, including without limitation prostaglandins and prostanoids (e.g., prostacyclin [prostaglandin I₂] and analogs thereof, such as beraprost, cicaprost and iloprost), other prostacyclin receptor agonists (e.g., selexipag and ACT-333679 [MRE-269]), calcium channel blockers (CCBs) (e.g., dihydropyridine-type CCBs [e.g., amlodipine and nifedipine] and non-dihydropyridine CCBs [e.g., diltiazem]), endothelin receptor (e.g., ET_(A) and/or ET_(B)) antagonists (e.g., ambrisentan, bosentan, sitaxentan and Actelion-1), phosphodiesterase type 5 (PDE5) inhibitors (e.g., avanafil, benzamidenafil, dynafil, lodenafil, mirodenafil, sildenafil, tadalafil, udenafil, vardenafil, dipyridamole, icariin, papaverine, propentofylline, zaprinast and T-1032), activators of soluble guanylate cyclase (e.g., cinaciguat and riociguat), and analogs, derivatives and salts thereof;

diuretics, including without limitation thiazide diuretics (e.g., bendroflumethiazide, chlorothiazide, epitizide and hydrochlorothiazide), thiazide-like diuretics (e.g., chlorthalidone, indapamide and metolazone), and analogs, derivatives and salts thereof;

anticoagulants, including without limitation vitamin K antagonists (e.g., acenocoumarol, atromentin, coumarin, phenindione, phenprocoumon and warfarin), direct thrombin inhibitors (e.g., argatroban, dabigatran, hirudin, lepirudin and bivalirudin), direct factor Xa inhibitors (e.g., apixaban, betrixaban, darexaban, edoxaban, eribaxaban, letaxaban and rivaroxaban), heparin and derivatives thereof (e.g., unfractionated heparin, low molecular weight heparin, fondaparinux and idraparinux), others (e.g., antithrombin, batroxobin and hementin), and analogs, derivatives, fragments and salts thereof; and

other kinds of therapeutic agents, including without limitation cardiac glycosides (e.g., digoxin, acetyldigoxin and digoxigenin) and oxygen therapy.

VIII. SYNTHESIS OF TREPROSTINIL DERIVATIVES

A treprostinil (Trp) derivative of Formula (I) in which R² is hydrogen and —OR¹ is derivatized can be prepared by reacting a Trp compound appropriately protected at the octyl hydroxyl group and the carboxyl group (e.g., Compound C in the Examples) with, e.g., a carboxylic acid in the presence of an activating agent (e.g., EDC, DCC, DIC, BOP-Cl, BOP reagent, HATU, HBTU or CDI), or with a pre-prepared activated carbonyl compound (e.g., an acid chloride). The coupling reaction can optionally include an additive (e.g., DMAP, HOSu, HOBT or HOAT) that accelerates the reaction, and can also optionally include a non-nucleophilic or nucleophilic base (e.g., TEA, DIPEA, N-methylmorpholine, pyridine or imidazole). The coupling reaction can be run in a suitable solvent or solvent mixture (e.g., DCM, DMF, THF, dioxane, ethyl acetate or acetonitrile, or any combination thereof). Coupling conditions and reagents, including activating agents, additives and bases, are discussed in, e.g., Handbook of Reagents for Organic Synthesis: Activating Agents and Protecting Groups, A. Pearson and W. Roush, Eds., John Wiley and Sons (1999). The bis-protected Trp compound derivatized at —OR¹ can be deprotected to furnish a Trp derivative of Formula (I) using reagents and conditions known in the art. See, e.g., P. Wuts and T. Greene, Greene's Protective Groups in Organic Synthesis, 4^(th) Ed., John Wiley and Sons (2006).

A Trp derivative of Formula (I) in which R¹ is hydrogen and —OR² is derivatized can be prepared by appropriately protecting the cyclopentyl hydroxyl group of Compound C, deprotecting the octyl hydroxyl group without deprotecting the cyclopentyl hydroxyl group or the carboxyl group, reacting the octyl hydroxyl group with an activated carbonyl compound (pre-prepared or prepared in situ), and deprotecting the cyclopentyl hydroxyl group and the carboxyl group. A Trp derivative of Formula (I) in which —OR¹ and —OR² are derivatized with different groups can be prepared by derivatizing —OR¹ of Compound C as described herein, deprotecting the octyl hydroxyl group, derivatizing —OR², and deprotecting the carboxyl group. A Trp derivative of Formula (I) in which —OR¹ and —OR² are derivatized with the same group can be prepared by deprotecting the octyl hydroxyl group of Compound C, derivatizing —OR¹ and —OR² as described herein, and deprotecting the carboxyl group.

A Trp derivative of Formula (II) can be prepared by reacting a Trp compound appropriately protected at the octyl hydroxyl group (e.g., Compound B in the Examples) with an alcohol whose carboxyl group is appropriately protected in the presence of an activating agent as described herein, and deprotecting the octyl hydroxyl group and the carboxyl group.

The synthesis of representative treprostinil derivatives is described in the Examples.

IX. REPRESENTATIVE EMBODIMENTS

The following embodiments of the disclosure are provided by way of example only:

1. A compound of Formula (I):

wherein:

R¹ and R² independently are hydrogen,

wherein:

-   -   R³ in each occurrence independently is alkyl, haloalkyl,         -alkylaryl, cycloalkyl, heterocyclyl, aryl or heteroaryl, each         of which may optionally be substituted;     -   R⁴ and R⁵ in each occurrence independently are hydrogen, C₁-C₆         alkyl or C₃-C₆ cycloalkyl, or R⁴ and R⁵ and the carbon atom to         which they are connected form a C₃-C₆ cycloalkyl ring;     -   R⁶ in each occurrence independently is hydrogen, R³, —C(═O)R³,         —C(═O)OR³ or —C(═O)NR⁹R¹⁰; or         -   R⁶ and R⁴ or R⁵, together with the atoms to which they are             connected, form a heterocyclic ring;     -   R⁹ and R¹⁰ in each occurrence independently are hydrogen, alkyl,         -alkylaryl, cycloalkyl, heterocyclyl, aryl or heteroaryl; or         -   R⁹ and R¹⁰ and the nitrogen atom to which they are connected             form a heterocyclic or heteroaryl ring;

j in each occurrence independently is an integer from 0 to 4;

m in each occurrence independently is an integer from 1 to 10; and

t in each occurrence independently is an integer from 1 to 9;

or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof, with the proviso that:

both R¹ and R² are not hydrogen;

neither —OR¹ nor —OR² forms an acetate;

neither —OR¹ nor —OR² forms a benzoate;

neither —OR¹ nor —OR² forms a substituted cyclohexane-ester;

neither —OR¹ nor —OR² forms an ester with or of an amino acid (protected or unprotected), a peptide or a protein; and

the compound of Formula (I) is not a homopolymer or heteropolymer of treprostinil, or does not contain more than one molecule or unit of treprostinil.

2. The compound of embodiment 1, wherein R³ in

is not alkyl substituted with a nitrogen-containing group, or not cycloalkyl substituted with a carbonyl-containing group. 3. The compound of embodiment 1, wherein neither the alkyl nor the cycloalkyl group, or none of the alkyl, haloalkyl, -alkylaryl, cycloalkyl, heterocyclyl, aryl or heteroaryl group, of R³ in

is substituted. 4. The compound of any one of the preceding embodiments, wherein j in each occurrence independently is 0, 1 or 2. 5. The compound of any one of the preceding embodiments, wherein m in each occurrence independently is an integer from 1 to 6, and/or t in each occurrence independently is an integer from 1 to 5. 6. The compound of any one of the preceding embodiments, wherein R¹ and R² independently are hydrogen,

and wherein:

R⁴, R⁵, R⁶ and m are as defined above; and

k in each occurrence independently is an integer from 1 to 9;

with the proviso that both R¹ and R² are not hydrogen.

7. The compound of embodiment 6, wherein k in each occurrence independently is an integer from 1 to 5.

8. The compound of any one of the preceding embodiments, wherein:

R³ in each occurrence independently is C₁-C₆ alkyl;

R⁴ and R⁵ in each occurrence independently are hydrogen or C₁-C₃ alkyl, or R⁴ and R⁵ and the carbon atom to which they are connected form a cyclopropyl ring;

R⁶ in each occurrence independently is hydrogen or R³;

R⁹ and R¹⁰ in each occurrence independently are C₁-C₆ alkyl, or R⁹ and R¹⁰ and the nitrogen atom to which they are connected form a 3- to 6-membered heterocyclic ring;

j in each occurrence independently is 0 or 1;

m in each occurrence independently is 1 or 2; and

t in each occurrence independently is 1 or 2.

9. The compound of embodiment 8, wherein:

R³ in each occurrence independently is methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl or tert-butyl;

R⁴ and R⁵ in each occurrence independently are hydrogen, methyl, ethyl, propyl or isopropyl;

R⁶ in each occurrence independently is hydrogen or R³;

R⁹ and R¹⁰ in each occurrence independently are C₁-C₃ alkyl;

j is 0;

m is 1; and

t is 1.

10. The compound of any one of the preceding embodiments, wherein R¹ and R² independently are selected from the group consisting of:

hydrogen,

with the proviso that both R¹ and R² are not hydrogen.

11. The compound of embodiment 10, wherein R¹ and R² independently are selected from the group consisting of:

hydrogen,

with the proviso that both R¹ and R² are not hydrogen.

12. The compound of any one of the preceding embodiments, wherein both —OR¹ and —OR² are derivatized [Formula (Ic)], optionally with the same group.

13. The compound of any one of embodiments 1 to 11, wherein both —OR¹ and —OR² are not derivatized.

14. The compound of embodiment 13, wherein R² is hydrogen and —OR¹ is derivatized [Formula (Ia)].

15. The compound of embodiment 13, wherein R¹ is hydrogen and —OR² is derivatized [Formula (Ib)].

16. The compound of any one of the preceding embodiments, which is selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof. 17. A compound selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof. 18. A compound of Formula (II):

wherein:

—O—Z—CO₂H is

—O-heteroalkyl-CO₂H, —O-cyclyl-CO₂H, —O—CH₂-cyclyl-CO₂H, —O-cyclyl-CH₂—CO₂H, or —O—CH₂-cyclyl-CH₂—CO₂H, each of which may optionally be substituted,

wherein:

-   -   -cyclyl- is -cycloalkyl-, -heterocyclyl-, -aryl- or         -heteroaryl-;     -   R⁷ and R⁸ in each occurrence independently are hydrogen, C₁-C₆         alkyl or C₃-C₆ cycloalkyl, or R⁷ and R⁸ and the carbon atom to         which they are connected form a C₃-C₆ cycloalkyl ring; and     -   n is an integer from 1 to 10;         or a pharmaceutically acceptable salt, solvate, hydrate,         clathrate, polymorph or stereoisomer thereof, with the proviso         that:

—O—Z—CO₂H is not

and

—O—Z—CO₂H does not contain a sugar moiety.

19. The compound of embodiment 18, wherein n is an integer from 1 to 6.

20. The compound of embodiment 18, wherein n is an integer from 3 to 10, or from 3 to 6.

21. The compound of embodiment 18, wherein —O—Z—CO₂H is not

22. The compound of embodiment 18, wherein each occurrence of R⁷ and R⁸ is hydrogen when n is 1 or 2. 23. The compound of embodiment 18, wherein each occurrence of R⁷ and R⁸ is hydrogen, and n is an integer from 1 to 10, or from 1 to 6. 24. The compound of embodiment 18, wherein —O—Z—CO₂H does not contain a -heterocyclyl- group, or a substituted -heterocyclyl- group. 25. The compound of embodiment 18, wherein —O—Z—CO₂H is

and wherein:

R⁷ and R⁸ are as defined above;

p is an integer from 1 to 9; and

q is an integer from 0 to 8;

with the proviso that —O—Z—CO₂H is not

26. The compound of embodiment 25, wherein p is an integer from 1 to 5, and q is an integer from 0 to 4. 27. The compound of embodiment 25 or 26, wherein both R⁷ and R⁸ are hydrogen, and p is an integer from 1 to 5 or from 1 to 3 (or each occurrence of R⁷ and R⁸ is hydrogen, and q is an integer from 0 to 4 or from 0 to 2). 28. The compound of embodiment 25 or 26, wherein —O—Z—CO₂H is

and p is 2, 3, 4 or 5. 29. The compound of embodiment 18, wherein —O—Z—CO₂H is —O-heteroalkyl-CO₂H, and —O-heteroalkyl-CO₂H is selected from the group consisting of:

wherein r is each of 1, 2 and 3. 30. The compound of embodiment 29, wherein —O—Z—CO₂H is

and r is 1, 2 or 3. 31. The compound of embodiment 18, wherein —O—Z—CO₂H is —O-cycloalkyl-C₂H, —O—CH₂-cycloalkyl-CO₂H, —O-cycloalkyl-CH₂—CO₂H, or —O—CH₂-cycloalkyl-CH₂—CO₂H, and for each of the preceding moieties -cycloalkyl- is:

1,2-cyclopropyl (cis or trans); or

1,3-cyclobutyl (cis or trans) or 1,2-cyclobutyl (cis or trans); or

1,3-cyclopentyl (cis or trans) or 1,2-cyclopentyl (cis or trans); or

1,4-cyclohexyl (cis or trans), 1,3-cyclohexyl (cis or trans), or 1,2-cyclohexyl (cis or trans).

32. The compound of embodiment 31, wherein —O—Z—CO₂H is selected from the group consisting of:

33. The compound of any one of embodiments 18 to 32, which is selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof. 34. The compound of embodiment 33, which is selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof. 35. A compound selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof. 36. The compound of embodiment 35, which is selected from the group consisting of:

and pharmaceutically acceptable salts, solvates, hydrates, clathrates, polymorphs and stereoisomers (including enantiomers and racemic mixtures) thereof. 37. A pharmaceutical composition comprising a compound of any one of embodiments 1 to 36, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof, and one or more pharmaceutically acceptable excipients or carriers. 38. The composition of embodiment 37, wherein the compound is a compound of embodiment 17 or 35, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof. 39. The composition of embodiment 38, wherein the compound is a compound of embodiment 17 or 36, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof. 40. The composition of any one of embodiments 37 to 39, which is configured or formulated for transdermal delivery of the compound. 41. The composition of embodiment 40, which is configured or formulated as a transdermal patch. 42. A method of treating a medical condition responsive to treatment with treprostinil, comprising administering to a subject in need of treatment a therapeutically effective amount of a compound of any one of embodiments 1 to 36, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof. 43. The method of embodiment 42, wherein the medical condition is selected from the group consisting of pulmonary hypertension, pulmonary fibrosis, interstitial lung disease, asthma, congestive heart failure, peripheral vascular disease, severe intermittent claudication, atherogenesis (e.g., atherosclerosis), ischemic lesions (e.g., peripheral ischemic lesions on the skin, such as those caused by Buerger's disease, Raynaud's phenomenon, Raynaud's disease, scleroderma and systemic sclerosis), critical limb ischemia, neuropathic foot ulcers (e.g., diabetic neuropathic foot ulcer), kidney malfunction and failure, immunosuppression, proliferative disorders (e.g., tumors and cancers, such as those of the head and neck, brain, lung, liver, kidney, pancreas, gastrointestinal tract [e.g., colon], prostate and breast), and pain associated with each of the preceding conditions. 44. The method of embodiment 43, wherein the medical condition is pulmonary hypertension. 45. The method of embodiment 44, wherein the medical condition is pulmonary arterial hypertension. 46. The method of any one of embodiments 42 to 45, wherein the compound is a compound of embodiment 17 or 35, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof. 47. The method of embodiment 46, wherein the compound is a compound of embodiment 17 or 36, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof. 48. The method of any one of embodiments 42 to 47, wherein the route of administration of the compound comprises oral, parenteral (e.g., intradermal, subcutaneous, intramuscular, intravascular, intravenous, intraarterial, intramedullary or intrathecal), intracavitary, intraperitoneal, or topical (e.g., dermal/epicutaneous, transdermal, mucosal, transmucosal, intranasal [e.g., by nasal spray or drop], intraocular [e.g., by eye drop], pulmonary [e.g., by inhalation], buccal, sublingual, rectal or vaginal), or any combination thereof. 49. The method of embodiment 48, wherein the compound is administered transdermally (e.g., via a transdermal patch). 50. The method of any one of embodiments 42 to 49, wherein:

the medical condition is pulmonary arterial hypertension;

the compound is a compound of embodiment 17 or 35, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof; and

the compound is administered transdermally (e.g., via a transdermal patch).

51. The method of any one of embodiments 42 to 50, further comprising administering an additional therapeutic agent.

52. The method of embodiment 51, wherein the additional therapeutic agent comprises a vasoactive agent, a diuretic, an anticoagulant or a cardiac glycoside, or any combination thereof.

53. A kit comprising:

a compound of any one of embodiments 1 to 36, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof; and

instructions for administering the compound to treat a medical condition responsive to treatment with treprostinil.

54. The kit of embodiment 53, wherein the compound is contained or incorporated in a device or system configured for transdermal delivery (e.g., a transdermal patch).

55. The kit of embodiment 53 or 54, wherein the medical condition is pulmonary hypertension (e.g., pulmonary arterial hypertension).

X. EXAMPLES

The following examples are intended only to illustrate the disclosure. Other procedures, methodologies, assays, conditions and reagents may alternatively be used as appropriate.

Biological Assays of Treprostinil Derivatives Example 1. Stability Assays of Treprostinil Derivatives

The following three stability assays were conducted on treprostinil derivatives, with the results shown in Table 1.

(Test 1) Human liver microsomal stability assay was conducted by incubating 0.5 μM test compound at 37° C. for up to 45 minutes in 50 mM potassium phosphate buffer (pH 7.4) containing 0.5 mg of microsomal protein and 50 μL of NADPH-generating system (7.8 mg of glucose 6-phosphate, 1.7 mg of NADPH and 6 U of glucose 6-phosphate dehydrogenase per mL in 2% w/v of sodium bicarbonate). At 0, 5, 15, 30 and 45 min, an aliquot was taken and quenched with internal standard-containing stop solution. No co-factor controls at 45 min were prepared. After incubation, the samples were analyzed by LC-MS/MS. Peak area ratios of analyte to internal standard were used to calculate the intrinsic clearance. The intrinsic clearance (CL_(int)) was determined from the first-order elimination constant by non-linear regression. Formation of the active drug treprostinil (Compound A) over the time course was monitored by LC-MS/MS analysis.

(Test 2) Human plasma stability assay was conducted by incubating 0.5 μM test compound at 37° C. for up to 120 min in heparinated human plasma. At 0, 5, 15, 30, 60, 120 and 240 min, an aliquot was taken and quenched with internal standard-containing stop solution. After incubation, the samples were analyzed by LC-MS/MS. Peak area ratios of analyte to internal standard were used to calculate the half-life. Formation of the active drug Compound A over the time course was monitored by LC-MS/MS analysis.

(Test 3) Human skin homogenate stability assay was conducted in a similar manner as the human liver microsomal stability assay, by incubating 0.5 μM test compound at 37° C. for up to 45 min in 50 mM potassium phosphate buffer (pH 7.4) containing 0.5 mg of human skin homogenate protein and 50 μL of NADPH-generating system (7.8 mg of glucose 6-phosphate, 1.7 mg of NADPH and 6 U of glucose 6-phosphate dehydrogenase per mL in 2% w/v of sodium bicarbonate). At 0, 5, 15, 30 and 45 min, an aliquot was taken and quenched with internal standard-containing stop solution. No co-factor controls at 45 min were prepared. After incubation, the samples were analyzed by LC-MS/MS. Peak area ratios of analyte to internal standard were used to calculate the intrinsic clearance. The intrinsic clearance (CL_(int)) was determined from the first-order elimination constant by non-linear regression. Formation of the active drug Compound A over the time course was monitored by LC-MS/MS analysis.

Results (half-life) of the three stability assays described above are shown in Table 1. For Table 1, the code for the half-life of the test compounds in the assays is:

A=<15 min

B=15-30 min

C=31-60 min

D=>60 min

TABLE 1 MW m/z Test 1 Test 2 Test 3 Cmpd No. (g/mol) [M + Na]⁺ T_(1/2) T_(1/2) T_(1/2) Test 4 A 390 413 +++ +++ Ia-1 446 469 A D D + + + Ia-3 474 497 A D D +++ +++ Ia-7 448 471 A D D ++ Ia-8 462 485 A D D +++ +++ ++ Ia-9 476 499 A D D + Ia-10 448 471 A D D ++ ++ Ia-11 462 485 A D D ++ ++ ++ Ia-14 478 501 C D D +++ +++ +++ Ib-8 462 485 A D D + Ib-10 448 471 A D D II-1 448 471 C D D +++ ++ II-2 462 485 C D D ++++ ++++ ++++ II-4 462 485 B D D +++ +++

Example 2. Skin Permeability Assay of Treprostinil Derivatives

(Test 4) A skin permeability assay was performed using a vertical Franz diffusion cell having a diffusion area of 0.64 cm² and a volume of 7.5 mL. The assay was conducted at 32° C. with continuous stirring. Heat-separated human cadaver epidermis was used in the assay, the epidermis being stored at −20° C. after the heat stripping procedure. The human epidermis was thawed prior to being mounted on the diffusion cell. A test compound was applied on the skin, and the diffusion cell was closed by screw-cap. At various time intervals, whole medium or receptor medium was replaced by fresh medium. Part of the collected medium was used to calculate the cumulative skin permeability of the test compound at 72 hours. The skin permeability of various test compounds was evaluated using human epidermis from different donors. N=4 replicates were performed for each test compound tested on human epidermis from a particular donor.

Results of the skin permeability assay are shown in Table 1 above. For Table 1, the code for the cumulative skin permeability at 72 hours of the test compounds tested on human epidermis from a particular donor is:

+=low to moderate skin permeability

++=medium skin permeability

+++=high skin permeability

++++=very high skin permeability

Synthesis of Treprostinil Derivatives

Representative syntheses of compounds of Formulas (I) and (II) are shown below.

Synthesis of {2-hydroxy-1-[3-(tetrahydropyran-2-yloxy)octyl]-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy}acetic Acid Benzyl Ester (Compound C)

A solution of {2-hydroxy-1-[3-(tetrahydropyran-2-yloxy)octyl]-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy}acetic acid (Compound B) (2 g, 4.21 mmol), benzyl alcohol (2.47 g, 22.9 mmol) and triethylamine (7.2 g, 71.3 mmol) in dichloromethane (DCM) (20 mL) was treated with bis(2-oxo-3-oxazolidinyl)phosphinic chloride (BOP-Cl) (7.8 g, 30.7 mmol) at 0° C. and stirred at room temperature (RT) for 2 hr. The reaction mixture was diluted with methyl-tert-butyl ether (MTBE) and washed with water and then brine, dried over sodium sulfate and concentrated under vacuum. The residue was purified by silica gel chromatography to provide Compound C. MS: m/z 587 [M+Na]⁺

Example 3. Synthesis of [1-(3-hydroxyoctyl)-2-(2-methoxyacetoxy)-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy]acetic Acid (Compound Ia-8)

A solution of Compound C (90 mg, 0.15 mmol), NEt₃ (70 μL, 0.5 mmol) and 4-dimethylaminopyridine (DMAP) (1 crystal) in DCM (2 mL) was treated with methoxyacetyl chloride (21 μL, 0.22 mmol) and stirred at RT for 12 hr under nitrogen. The reaction mixture was diluted with MTBE and washed with water and then brine, dried over sodium sulfate and concentrated under vacuum. The residue was purified by silica gel chromatography. The THP-protected methoxyacetate was dissolved in MeOH (4 mL), treated with pyridinium para-toluene-sulfonate (PPTS) (catalytic) and stirred at 50° C. for 2 hr. The reaction mixture was concentrated, and the residue was dissolved in MTBE (20 mL) and washed with water and then brine to yield crude THP-deprotected methoxyacetate. The crude product was taken in dioxane (5 mL) along with 10% Pd/C (18 mg) and hydrogenated under a hydrogen atmosphere to yield crude Compound Ia-8 (64 mg) as an oil. MS: m/z 485 [M+Na]⁺

The following compounds were synthesized using similar procedures as above:

Example 4. Synthesis of [2-(2-hydroxyacetoxy)-1-(3-hydroxyoctyl)-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy]acetic Acid (Compound Ia-7)

A solution of Compound C (100 mg, 0.177 mmol), NEt₃ (77 μL, 0.55 mmol) and DMAP (1 crystal) in DCM (2 mL) was treated with benzyloxyacetyl chloride (65 mg, 0.22 mmol) and stirred at RT for 12 hr under nitrogen. The reaction mixture was diluted with MTBE and washed with water and then brine, dried over sodium sulfate and concentrated under vacuum. The residue was purified by silica gel chromatography. The THP-protected benzyloxyacetate was dissolved in MeOH (4 mL), treated with PPTS (catalytic) and stirred at 50° C. for 2 hr. The reaction mixture was concentrated, and the residue was dissolved in MTBE (20 mL) and washed with water and then brine to yield crude THP-deprotected benzyloxyacetate. The crude product was taken in dioxane (5 mL) along with 10% Pd/C (24 mg) and hydrogenated under a hydrogen atmosphere to yield crude Compound Ia-7 (56 mg) as an oil. MS: m/z 471 [M+Na]⁺

Example 5. Synthesis of [1-(3-hydroxyoctyl)-2-methoxycarbonyloxy-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy]acetic Acid (Compound Ia-10)

A solution of Compound C (160 mg, 0.28 mmol) and NEt₃ (798 μL, 2.8 mmol) in DCM (2 mL) was treated with phosgene solution (906 μL, 1.4 mmol, 0.5 M in toluene) at 0° C., and the resulting mixture was stirred at 0° C. for 0.5 hr under nitrogen. The reaction mixture was then added to MeOH (2 mL) at 0° C. and stirred for an additional 1 hr. The solvent was removed, and the residue was purified by silica gel chromatography. The THP-protected methylcarbonate was dissolved in MeOH (4 mL), treated with PPTS (catalytic) and stirred at 50° C. for 2 hr. The reaction mixture was concentrated, and the residue was dissolved in MTBE (20 mL) and washed with water and then brine to yield crude THP-deprotected methylcarbonate. The crude product was taken in dioxane (5 mL) along with 10% Pd/C (28 mg) and hydrogenated under a hydrogen atmosphere to yield crude Compound Ia-10 (83 mg) as an oil. MS: m/z 471 [M+Na]⁺

The following compound was synthesized using similar procedures as above:

Synthesis of [2-benzyloxycarbonyloxy-1-(3-hydroxyoctyl)-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy]acetic Acid Benzyl Ester (Compound D)

A solution of Compound C (100 mg, 0.177 mmol), NEt₃ (77 μL, 0.55 mmol) and DMAP (I crystal) in DCM (2 mL) was treated with N-(benzyloxycarbonyloxy)succinimide (84 mg, 0.34 mmol) and stirred at RT for 24 hr under nitrogen. The reaction mixture was diluted with MTBE and washed with water and then brine, dried over sodium sulfate and concentrated under vacuum. The residue was purified by silica gel chromatography. The benzylcarbonate was dissolved in MeOH (4 mL), treated with PPTS (catalytic) and stirred at 50° C. for 2 hr. The reaction mixture was concentrated, and the residue was dissolved in MTBE (20 mL) and washed with water and then brine to yield crude Compound D (110 mg) as an oil.

Example 6. Synthesis of {2-hydroxy-1-[3-(2-methoxyacetoxy)octyl]-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy}acetic Acid (Compound Ib-8)

A solution of Compound D (70 mg, 0.11 mmol), NEt₃ (75 μL, 0.52 mmol) and DMAP (1 crystal) in DCM (2 mL) was treated with methoxyacetyl chloride (21 μL, 0.22 mmol) and stirred at 0° C. for 1 hr under nitrogen. The reaction mixture was diluted with MTBE and washed with water and then brine, dried over sodium sulfate and concentrated under vacuum. The residue was purified by silica gel chromatography. The methoxyacetate was taken in dioxane (5 mL) along with 10% Pd/C (16 mg) and hydrogenated under a hydrogen atmosphere to yield crude Compound Ib-8 (43 mg) as an oil. MS: m/z 485 [M+Na]⁺

The following compounds were synthesized using similar procedures as above:

Example 7. Synthesis of 3-{2-[2-hydroxy-1-(3-hydroxyoctyl)-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yloxy]acetoxy}propionic Acid (Compound II-4)

To a solution of Compound B (120 mg, 0.25 mmol), benzyl 3-hydroxypropionate (54 mg, 0.30 mmol) and trimethylamine (140 μL, 1.0 mmol) in DCM (4 mL) was added BOP-Cl (95 mg, 0.38 mmol). The reaction mixture was stirred at RT for 16 hr under nitrogen, diluted with MTBE, washed with brine, dried over sodium sulfate, and concentrated to an oil that was purified by silica gel chromatography. A solution of the THP-protected diester in ethanol (4 mL) was treated with PPTS (50 mg), stirred at 50° C. for 4 hr, and concentrated to an oil that was purified by silica gel chromatography. A solution of the THP-deprotected diester in dioxane (5 mL) was treated with wet 5% Pd/C (20 mg) and stirred for 24 hr under a balloon of hydrogen. The reaction mixture was filtered and concentrated to give crude Compound II-4. MS: m/z 485 [M+Na]⁺

The following compounds were synthesized using similar procedures as above:

It is understood that, while particular embodiments have been illustrated and described, various modifications may be made thereto and are contemplated herein. It is also understood that the disclosure is not limited by the specific examples provided herein. The description and illustration of embodiments and examples of the disclosure herein are not intended to be construed in a limiting sense. It is further understood that all aspects of the disclosure are not limited to the specific depictions, configurations or relative proportions set forth herein, which may depend upon a variety of conditions and variables. Various modifications and variations in form and detail of the embodiments and examples of the disclosure will be apparent to a person skilled in the art. It is therefore contemplated that the disclosure also covers any and all such modifications, variations and equivalents. 

What is claimed is:
 1. A compound selected from the group consisting of:

or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof.
 2. A pharmaceutical composition comprising the compound of claim 1, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof, and one or more pharmaceutically acceptable excipients or carriers.
 3. The pharmaceutical composition of claim 2, which is formulated for oral administration of the compound.
 4. The pharmaceutical composition of claim 2, which is formulated for parenteral administration of the compound.
 5. The pharmaceutical composition of claim 4, which is formulated for intravenous or subcutaneous administration of the compound.
 6. The pharmaceutical composition of claim 2, which is formulated for topical administration of the compound.
 7. The pharmaceutical composition of claim 6, which is formulated for transdermal administration or pulmonary administration by inhalation of the compound.
 8. A method of treating a medical condition responsive to treatment with treprostinil, comprising administering to a subject in need of treatment a therapeutically effective amount of the compound of claim 1, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof.
 9. The method of claim 8, wherein the medical condition is selected from the group consisting of pulmonary hypertension, pulmonary arterial hypertension, pulmonary fibrosis, interstitial lung disease, cardiovascular disease, heart failure, congestive heart failure, conditions requiring anticoagulation, thrombotic microangiopathy, central retinal vein occlusion, ischemic diseases, peripheral vascular disease, critical limb ischemia, atherogenesis, peripheral ischemic lesions on the skin, diabetic neuropathic foot ulcers, inflammatory diseases, kidney malfunction and failure, and conditions of unregulated cell growth.
 10. The method of claim 9, wherein the medical condition is pulmonary arterial hypertension.
 11. The method of claim 8, wherein the compound is administered orally.
 12. The method of claim 8, wherein the compound is administered parenterally.
 13. The method of claim 12, wherein the compound is administered intravenously or subcutaneously.
 14. The method of claim 8, wherein the compound is administered topically.
 15. The method of claim 14, wherein the compound is administered transdermally or pulmonarily by inhalation.
 16. A transdermal patch comprising the compound of claim 1, or a pharmaceutically acceptable salt, solvate, hydrate, clathrate, polymorph or stereoisomer thereof.
 17. The transdermal patch of claim 16, further comprising a drug reservoir and a semi-permeable membrane, or a drug/polymer matrix.
 18. The transdermal patch of claim 16, further comprising a chemical permeation enhancer. 